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Holz als Roh- und Werkstoff

, Volume 63, Issue 6, pp 442–448 | Cite as

The impact of log-end splits and spring on sawn recovery of 32-year-old plantation Eucalyptus globulus Labill.

  • J.L. YangEmail author
ORIGINALARBEITEN ORIGINALS

Abstract

Thirty dominant or co-dominant, straight trees were selected from a 32-year-old thinned plantation of Eucalyptus globulus Labill. Growth strain at tree surface at breast height was estimated using a CIRAD-forêt method. Log-end splits in the butt logs were measured. The butt logs were quarter-sawn following a pre-determined sawing pattern. The most common dimensions of sawn boards were 28×105×3000and 28×77×3000 mm.The volume of the curved-edge off-cuts was estimated for each butt log. The end splits in the dried sawn boards were measured and the volume of the wood containing the splits in the boards calculated.

The estimated reduction in sawn recovery due to removing the curved edges in the slabs was equivalent to 6% of the log volume. The estimated reduction in recovery due to end-docking log-end splits was equivalent to 1% of the log volume, or approximately 4% of the dried board volume. For a sawmill processing 40000 m3 of logs per annum, this could translate into an annual loss of $ 758000 (log volume) and $ 385000 (board volume). These numbers are high in the context that end splits in these logs overall were quite mild and the estimated strain at tree surface was moderate.

Keywords

Growth Stress Tension Wood Eucalyptus Globulus Split Index Split Length 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Auswirkung von Kernrissen und Längskrümmung auf die Ausbeute von 32-jährigem Plantagen-Eukalyptus (Eucalyptus globulus Labill.)

Zusammenfassung

Dreissig herrschende bzw. mitherrschende, geradschaftige Stämme wurden auf einer Durchforstungsfläche mit 32-jährigem Eukalyptus (Eucalyptus globulus Labill.) ausgewählt. Wachstumsspannungen an der Stammoberfläche in Brusthöhe wurden mittels einer CIRAD-Forst Methode geschätzt. Die Erdstammstücke wurden im Kreuzholzschnitt eingeschnitten, nachdem an diesen die Risse am Hirnholz gemessen worden waren. Die häufigsten Masse der eingeschnittenen Bretter waren 28×105×3000 mm und 28×77×3000 mm. Für jeden Erdstammabschnitt wurde das beim Besäumen abgetrennte Holzvolumen geschätzt. In den eingeschnittenen und getrockneten Brettern wurden die vom Hirnholz ausgehenden Risse gemessen und das davon betroffene Holzvolumen errechnet.

Der geschätzte Ausbeuteverlust durch das Besäumen entsprach 6% des Rundholzvolumens. Erforderliche Kürzungen infolge der vom Hirnholz ausgehenden Risse verringerten die Ausbeute um 1% bezogen auf das Rundholzvolumen bzw. etwa um 4% bezogen auf das Volumen der getrockneten Bretter. Für ein Sägewerk mit einer Einschnittkapazität von 40000 m3 pro Jahr könnte sich dies in einem jährlichen Verlust von $ 758000 (Rundholz) und. $ 385000 (Schnittholz) niederschlagen. Diese Zahlen sind hoch, gemessen an der Tatsache, dass die Rissbildung in den untersuchten Stämmen schwach ausgeprägt und die geschätzten Wachstumsspannungen an der Stammoberfläche mässig waren.

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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  1. 1.Ensis - Wood and Fibre QualityClayton SouthAustralia

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